1. Field of the Invention
The invention relates generally to joint prostheses, and more particularly to an ankle joint prosthesis that can be set in either of two fixed positions for walking and swimming, respectively, or a free-flexing mode suitable for activities such as skiing or rowing.
2. Description of the Related Art
The following patents may be relevant to the present invention:
______________________________________ Patent No. Inventor Issue Date ______________________________________ 667,511 I. R. Fenner et al. February 5, 1901 1,123,928 J. F. Rowley January 5, 1915 2,617,115 E. C. Ellery November 11, 1952 2,692,990 E. R. Schaefer November 2, 1954 2,749,557 G. P. Riddle June 12, 1956 3,480,972 G. Prahl December 2, 1969 3,546,712 M. C. Tarte December 15, 1970 3,597,767 J. Prahl August 10, 1971 3,649,968 J. Prahl March 21, 1972 3,800,333 K. A. Frieberg April 2, 1974 4,283,800 M. T. Wilson August 18, 1981 4,413,360 S. R. Lamb et al. November 8, 1983 ______________________________________
U.S. Pat. No. 2,749,557 to Riddle is directed to an adjustable ankle joint for use on an artificial limb. The ankle portion 13 of artificial limb 11 pivotally couples the foot portion 14 to the leg portion 12 by means of pins or studs 15. The angular position of the foot portion relative to the leg portion is lockingly maintained in angular relationship by means of a locking rod 24 which passes through the pivoted ankle joint for coupling with one of a plurality of recesses 39 formed in member 20 of foot portion 14. The locking rod is operated by means of a lever 28.
U.S. Pat. No. 3,546,712 to Tarte is directed to an artificial leg having means for retaining the joint in a relatively locked condition. The knee joint pivotally couples the upper leg element and the lower leg element by means of the pin 18. The joint is lockable by means of the rod 22 which extends from the foot element 16 into the upper leg element 12. When the end 24 of rod 22 is captivated within the socket 31 of upper leg 12, the knee joint is locked, preventing pivotal movement. However, the pin of rod 22 is engaged from the socket 31 by lifting the leg, allowing the heel 46 to drop, thereby allowing the rod to withdraw from the socket.
U.S. Pat. No. 4,413,360 to Lamb et al. is directed to an adjustable prosthetic ankle having a pivotable foot portion which may be secured in a desired position. The ankle assembly comprises an ankle member 16 which adjustably couples a foot member 18 to a shin member 14. The ankle member 16 is pivoted with a mechanism 20 comprising a yoke 24 pivotally coupled to a rocker block 46. The pivotal coupling is provided by two cross rocker block 46. The pivotal eccentrically positioned clamp holes 36 and through a pair of cylindrical pivot inserts 38 which flex and clamp around cross pins 34 when the adjustment mechanism is tightened by the user. Clamping screws 38 may be tightened to a locking position of the ankle joint.
U.S. Pat. No. 1,123,928 to Rowley is directed to an ankle joint for use with an artificial limb. The upper block comprises a threaded shank 1 having a pair of arms 3 terminating in a pair of co-axially aligned cylinders 4 formed in one end. The lower block comprises a bearing member 5 coupled with a threaded shank 10, while the cylinders 4 of the upper block are coupled to the bearing member 5 for pivotal coupling therebetween. No means for locking the position of the ankle is provided.
U.S. Pat. No. 2,617,115 to Ellery is directed to an ankle joint for artificial limbs. The ankle joint 15 includes an upper block 16 pivotably coupled to a lower block 17 by means of the pivot pin 32. No means for adjustably locking the position of the joint is provided.
Although each of the ankle joint prostheses discussed above possesses certain desirable features, all suffer from one or more deficiencies. Most conventional ankle joint prostheses are designed primarily for walking and do not allow the position of the foot to be changed for different activities. Or, if an ankle prosthesis is designed to be adjustable, the adjustment requires a special tool or cannot be made rapidly and conveniently. Special sports prostheses have been designed, but these are usually for one particular type of athletic activity, and a person must switch to a different special prosthesis to engage in a different sport.
There has been a long-felt need for an ankle joint prosthesis which can be used for a range of different activities, can be quickly and easily adjusted from one position to another, and which is lightweight, strong, and waterproof. To date, although several attempts have been made by numerous other skilled inventors to achieve all of these desirable operational capabilities, no ankle joint prosthesis has been designed or built that has satisfied the necessary criteria.